<!DOCTYPE html>
<html lang="en">
<link rel="stylesheet" href="/css/bootstrap.min.css">
<head>
    <meta charset="UTF-8">
    <title>欢迎页面</title>

    <style>
        .jumbotron{
            text-align: center;
            color: white;
            background: linear-gradient(45deg,#020031,#6d3353);
        }
        .a{
            width:200px;
            height:200px;
            position:absolute;
            top:50%;
            left:50%;
            transform:translate(-50%,-50%);
        }
    </style>

</head>
<body class="jumbotron">
<div class="a" style="font-size:100px">欢迎</div>
</body>
</html>